The overall objective of this core is to provide technical services and advice so that experiments can be complemented with morphological data. Essentially, the core cuts and stains tissue samples for light and electron microscopy (embedded in glycol methacrylate or epon, respectively), performs light and electron microscopy and helps in interpretation of results, and prepares frozen sections for enzyme histochemistry and immunocytochemistry. A computerized image analyzer is available for video imaging, image processing, quantitative morphometry and printing. Material is stored by digital imaging and image archiving, obviating the need to store slides in and retrieve from boxes. The core operates on a first come, first serve basis. Furthermore, efforts are made to provide training and advice to investigators and their technicians do work themselves, since the personnel resources of the core are limited. Detailed logs are kept to document samples processed and another log notes time spent by core staff on different projects. Costwise, the core claims to operate way under the cost a commercial service would provide while giving more attention to special needs and techniques; furthermore, many of the services provided by the core would not be available by a commercial service.